1. Technical Field to Which the Invention Belongs
The present invention relates to a vehicle control system for controlling a vehicle on the basis of a road shape ahead of the vehicle, as decided on the basis of map data comprised of a set of coordinate points.
2. Discussion of Relevant Art
According to a previous proposal (i.e., Japanese Patent Application Laid-Open No. 6-281471) of the Assignee, a passable zone is set on a map on the basis of map data obtained from a navigation system, so that when a curve in the road ahead of the subject vehicle of the driver goes out the passable zone, a warning is issued to urge the driver to decelerate the vehicle, or an automatic braking or the like is actuated to effect an automatic deceleration.
Although the previously proposed system is effective for its intended purpose, more or less errors are present in the map data obtained from the navigation system so that they unavoidably are reflected in the actual position of the vehicle determined on the basis of the map data. As a result, when the vehicle is to be decelerated at a predetermined rate from its actual position to a curve ahead, the estimated passage speed of the vehicle at the curve is dispersed from its optimum value by the errors of the actual position, thereby causing a reduction in the system's accuracy for deciding the passableness of the curve.